Federal officials have confirmed a “sophisticated set-up” of explosives in the Aurora, Colorado apartment of James Holmes, the man suspected of killing 12 people and wounding 58 others at a movie screening late Thursday night.

Five nearby buildings have been evacuated, and law enforcement officials are discussing ways of detonating or disarming the explosives, according to media reports on the ground.

Aurora police chief Daniel Oates said the apartment was booby-trapped with various incendiary devices and chemical devices connected to trip wires. He added that the explosives are so complex, “police could be on the scene for hours or days.”

The police used robots to examine the suspect’s residence without putting officers’ lives in danger. Now they plan to detonate the devices remotely rather than try to defuse them.

Kaitlyn Fonzi, who lives in the apartment below, said that she heard loud techno-like, deep-bass reverberating music coming from Holmes’ flat around the time of the massacre. She went to check on it, but decided not to confront the owner of the flat despite the fact that the door was open.

“I’m concerned if I had opened the door, I would have set it off,” she said.

She said she believes the music was on a timer because it started about the time of the shootings.

According to the tenants, the building is quiet and populated largely by students and doctors affiliated with a nearby University of Colorado Denver medical campus.

Ben Leung, a 27-year-old pharmacy student, told local media he lives on the first floor of the same building as the suspect, James Holmes. In a phone interview Leung said only people affiliated with the University of Colorado at Denver are allowed to live in the building.

Leung said he went to bed shortly after midnight, then awoke when police in riot gear banged on his door and told him the building was being evacuated. “At that time I had no idea what was going on,” he said.

Meanwhile, the Pentagon spokesman has told reporters that US service members appear to be among the casualties of the shooting.

According to the Department of Defense, 2 Air Force reservists and 2 Navy service member were among the injured,and are being treated in a hospital.